1// Copyright 2016 Google Inc. All Rights Reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#include "time_zone_posix.h"
16
17#include <cstddef>
18#include <cstring>
19#include <limits>
20#include <string>
21
22namespace cctz {
23
24namespace {
25
26const char kDigits[] = "0123456789";
27
28const char* ParseInt(const char* p, int min, int max, int* vp) {
29 int value = 0;
30 const char* op = p;
31 const int kMaxInt = std::numeric_limits<int>::max();
32 for (; const char* dp = strchr(kDigits, *p); ++p) {
33 int d = static_cast<int>(dp - kDigits);
34 if (d >= 10) break; // '\0'
35 if (value > kMaxInt / 10) return nullptr;
36 value *= 10;
37 if (value > kMaxInt - d) return nullptr;
38 value += d;
39 }
40 if (p == op || value < min || value > max) return nullptr;
41 *vp = value;
42 return p;
43}
44
45// abbr = <.*?> | [^-+,\d]{3,}
46const char* ParseAbbr(const char* p, std::string* abbr) {
47 const char* op = p;
48 if (*p == '<') { // special zoneinfo <...> form
49 while (*++p != '>') {
50 if (*p == '\0') return nullptr;
51 }
52 abbr->assign(op + 1, static_cast<std::size_t>(p - op) - 1);
53 return ++p;
54 }
55 while (*p != '\0') {
56 if (strchr("-+,", *p)) break;
57 if (strchr(kDigits, *p)) break;
58 ++p;
59 }
60 if (p - op < 3) return nullptr;
61 abbr->assign(op, static_cast<std::size_t>(p - op));
62 return p;
63}
64
65// offset = [+|-]hh[:mm[:ss]] (aggregated into single seconds value)
66const char* ParseOffset(const char* p, int min_hour, int max_hour, int sign,
67 std::int_fast32_t* offset) {
68 if (p == nullptr) return nullptr;
69 if (*p == '+' || *p == '-') {
70 if (*p++ == '-') sign = -sign;
71 }
72 int hours = 0;
73 int minutes = 0;
74 int seconds = 0;
75
76 p = ParseInt(p, min_hour, max_hour, &hours);
77 if (p == nullptr) return nullptr;
78 if (*p == ':') {
79 p = ParseInt(p + 1, 0, 59, &minutes);
80 if (p == nullptr) return nullptr;
81 if (*p == ':') {
82 p = ParseInt(p + 1, 0, 59, &seconds);
83 if (p == nullptr) return nullptr;
84 }
85 }
86 *offset = sign * ((((hours * 60) + minutes) * 60) + seconds);
87 return p;
88}
89
90// datetime = ( Jn | n | Mm.w.d ) [ / offset ]
91const char* ParseDateTime(const char* p, PosixTransition* res) {
92 if (p != nullptr && *p == ',') {
93 if (*++p == 'M') {
94 int month = 0;
95 if ((p = ParseInt(p + 1, 1, 12, &month)) != nullptr && *p == '.') {
96 int week = 0;
97 if ((p = ParseInt(p + 1, 1, 5, &week)) != nullptr && *p == '.') {
98 int weekday = 0;
99 if ((p = ParseInt(p + 1, 0, 6, &weekday)) != nullptr) {
100 res->date.fmt = PosixTransition::M;
101 res->date.m.month = static_cast<int_fast8_t>(month);
102 res->date.m.week = static_cast<int_fast8_t>(week);
103 res->date.m.weekday = static_cast<int_fast8_t>(weekday);
104 }
105 }
106 }
107 } else if (*p == 'J') {
108 int day = 0;
109 if ((p = ParseInt(p + 1, 1, 365, &day)) != nullptr) {
110 res->date.fmt = PosixTransition::J;
111 res->date.j.day = static_cast<int_fast16_t>(day);
112 }
113 } else {
114 int day = 0;
115 if ((p = ParseInt(p, 0, 365, &day)) != nullptr) {
116 res->date.fmt = PosixTransition::N;
117 res->date.j.day = static_cast<int_fast16_t>(day);
118 }
119 }
120 }
121 if (p != nullptr) {
122 res->time.offset = 2 * 60 * 60; // default offset is 02:00:00
123 if (*p == '/') p = ParseOffset(p + 1, -167, 167, 1, &res->time.offset);
124 }
125 return p;
126}
127
128} // namespace
129
130// spec = std offset [ dst [ offset ] , datetime , datetime ]
131bool ParsePosixSpec(const std::string& spec, PosixTimeZone* res) {
132 const char* p = spec.c_str();
133 if (*p == ':') return false;
134
135 p = ParseAbbr(p, &res->std_abbr);
136 p = ParseOffset(p, 0, 24, -1, &res->std_offset);
137 if (p == nullptr) return false;
138 if (*p == '\0') return true;
139
140 p = ParseAbbr(p, &res->dst_abbr);
141 if (p == nullptr) return false;
142 res->dst_offset = res->std_offset + (60 * 60); // default
143 if (*p != ',') p = ParseOffset(p, 0, 24, -1, &res->dst_offset);
144
145 p = ParseDateTime(p, &res->dst_start);
146 p = ParseDateTime(p, &res->dst_end);
147
148 return p != nullptr && *p == '\0';
149}
150
151} // namespace cctz
152